Cell Durotaxis on Polyelectrolyte Multilayers with Photogenerated Gradients of Modulus

Abstract

Behaviors of rat aortic smooth muscle (A7r5) and human osteosarcoma (U2OS) cells on photocrosslinked polyelectrolyte multilayers (PEMUs) with uniform, or gradients of, moduli were investigated. The PEMUs were built layer-by-layer with the polycation poly(allylamine hydrochloride) (PAH) and a polyanion poly(acrylic acid) (PAA) that was modified with photoreactive 4-(2-hydroxyethoxy) benzophenone (PAABp). PEMUs with different uniform and gradients of modulus were generated by varying the time of uniform ultraviolet light exposure and by exposure through optical density gradient filters. Analysis of adhesion, morphology, cytoskeletal organization, and motility of the cells on the PEMUs revealed that A7r5 cells established a polarized orientation toward increasing modulus on shallow modulus gradients (approximately 4.7 MPa mm−1) and durotaxed toward stiffer regions on steeper gradients (approximately 55 MPa mm−1). In contrast, U2OS cells exhibited little orientation or durotaxis on modulus gradients. These results demonstrate the utility of photocrosslinked PEMUs to direct vascular and osteoblast cell behavior, a potential application for PEMU coatings on biomedical implants.

Collective epithelial cell sheet adhesion and migration on polyelectrolyte multilayers with uniform and gradients of compliance

“…[49] Epidermal cell sheets migrated from explanted scales on PAH-PEMUs as fast as or faster than did sheets on uncoated glass (Fig. 4).…”

“…PAH-PEMUs were photocrosslinked with no mask, with an edge mask to generate steep modulus gradients (35–120 MPa; ~1.5 mm long; ~55 MPa mm −1 ), and through an optical density mask to generate shallow modulus gradients (35–120 MPa; ~15 mm long; ~5.5 MPa mm −1 ) [49]. As it migrates out, the length of a migrating cell sheet can reach 2 mm in length, long enough to span the entire steep modulus gradient and to span a difference of 11 MPa on the shallow gradient.…”

“…In our previous studies, we demonstrated the biocompatibility of PAH/PAA PEMUs and analyzed the behavior of single cells on similar PAH-PEMUs containing steep and shallow modulus gradients. [49, 51]…”

Growth and motility of human skin fibroblasts on multilayer strong polyelectrolyte films

“…On the other hand, cell motility on the PEM surface is not well recognized in the literature. To the best of our knowledge there is only one study showing that rat aortic smooth muscle (A7r5) cells can migrate toward stiffer regions of PAH/PAA films [16]. Also, PEMs composed of two strong polyelectrolytes were not systematically investigated in the context of their cellular response.…”

Partially photodegradable hybrid hydrogels with elasticity tunable by light irradiation

“…It is therefore important to reproduce soft and stiff tissue microenvironments for these cells to exhibit the desired functions. Several research groups have previously reported techniques to control hydrogel stiffness [9,10] and stiffness gradients [11][12][13].…”